On Thu, Nov 26, 2020 at 07:39:33AM +0100, Greg Kroah-Hartman wrote: > On Thu, Nov 26, 2020 at 10:14:43AM +0530, Naresh Kamboju wrote: > > Linaro recently started building and testing with stable branches with > > clang. > > Stable 4.9 branch kernel built with clang 10 boot crashed on x86 and > > qemu_x86. > > We do not have base line results to compare with. > > > > steps to build and boot: > > # build kernel with tuxmake > > # sudo pip3 install -U tuxmake > > # tuxmake --runtime docker --target-arch x86 --toolchain clang-10 > > --kconfig defconfig --kconfig-add > > https://builds.tuxbuild.com/1kgtX7QEDmhvj6OfbZBdlGaEple/config > > # boot qemu_x86_64 > > # /usr/bin/qemu-system-x86_64 -cpu host -enable-kvm -nographic -net > > nic,model=virtio,macaddr=DE:AD:BE:EF:66:14 -net tap -m 1024 -monitor > > none -kernel kernel/bzImage --append "root=/dev/sda rootwait > > console=ttyS0,115200" -hda > > rootfs/rpb-console-image-lkft-intel-corei7-64-20201022181159-3085.rootfs.ext4 > > -m 4096 -smp 4 -nographic > > > > Crash log: > > --------------- > > [ 14.121499] Freeing unused kernel memory: 1896K > > [ 14.126962] random: fast init done > > [ 14.206005] PANIC: double fault, error_code: 0x0 > > [ 14.210633] CPU: 1 PID: 1 Comm: systemd Not tainted 4.9.246-rc1 #2 > > [ 14.216809] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS > > 2.2 05/23/2018 > > [ 14.224196] task: ffff88026e2c0000 task.stack: ffffc90000020000 > > [ 14.230105] RIP: 0010:[<ffffffff8117ec2b>] [<ffffffff8117ec2b>] > > proc_dostring+0x13b/0x1e0 > > [ 14.238374] RSP: 0018:000000000000000c EFLAGS: 00010297 > > [ 14.243676] RAX: 00005638939fb850 RBX: 000000000000000c RCX: > > 00005638939fb850 > > [ 14.250799] RDX: 000000000000000c RSI: 0000000000000000 RDI: > > 000000000000007f > > [ 14.257925] RBP: ffffc90000023d98 R08: ffffc90000023ef8 R09: > > 00005638939fb850 > > [ 14.265049] R10: 0000000000000000 R11: ffffffff8117f9e0 R12: > > ffffffff82479cf0 > > [ 14.272171] R13: ffffc90000023ef8 R14: ffffc90000023dd8 R15: > > 000000000000007f > > [ 14.279298] FS: 00007f57fbce8840(0000) GS:ffff880277880000(0000) > > knlGS:0000000000000000 > > [ 14.287384] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 14.293120] CR2: fffffffffffffff8 CR3: 000000026d58a000 CR4: > > 0000000000360670 > > [ 14.300243] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > > 0000000000000000 > > [ 14.307368] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: > > 0000000000000400 > > [ 14.314491] Stack: > > [ 14.316504] Call Trace: > > [ 14.318955] Code: c3 49 8b 10 31 f6 48 01 da 49 89 10 49 83 3e 00 > > 74 49 41 83 c7 ff 49 63 ff 4c 89 c9 0f 1f 40 00 48 39 fe 73 36 48 89 > > c8 48 89 dc <e8> b0 9d 3a 00 85 c0 0f 85 8c 00 00 00 84 d2 74 1f 80 fa > > 0a 74 > > [ 14.338906] Kernel panic - not syncing: Machine halted. > > [ 14.344123] CPU: 1 PID: 1 Comm: systemd Not tainted 4.9.246-rc1 #2 > > [ 14.350291] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS > > 2.2 05/23/2018 > > [ 14.357677] ffff880277888e80 ffffffff81518ae9 ffff880277888e98 > > ffffffff82971a10 > > [ 14.365129] 000000000000000f 0000000000000000 0000000000000086 > > ffffffff820c5d57 > > [ 14.372584] ffff880277888f08 ffffffff81175736 0000003000000008 > > ffff880277888f18 > > [ 14.380038] Call Trace: > > [ 14.382481] <#DF> [ 14.384406] [<ffffffff81518ae9>] > > dump_stack+0xa9/0x100 > > [ 14.389641] [<ffffffff81175736>] panic+0xe6/0x2a0 > > [ 14.394432] [<ffffffff810c9911>] df_debug+0x31/0x40 > > [ 14.399389] [<ffffffff81096312>] do_double_fault+0x102/0x140 > > [ 14.405128] [<ffffffff81ccc987>] double_fault+0x27/0x30 > > [ 14.410440] [<ffffffff8117f9e0>] ? proc_put_long+0xc0/0xc0 > > [ 14.416004] [<ffffffff8117ec2b>] ? proc_dostring+0x13b/0x1e0 > > [ 14.421739] <EOE> [ 14.423703] Kernel Offset: disabled > > [ 14.427209] ---[ end Kernel panic - not syncing: Machine halted. > > > > Reported-by: Naresh Kamboju <naresh.kamb...@linaro.org> > > > > full test log, > > https://lkft.validation.linaro.org/scheduler/job/1978901#L916 > > https://lkft.validation.linaro.org/scheduler/job/1980839#L578 > > Is the mainline 4.9 tree supposed to work with clang? I didn't think > that upstream effort started until 4.19 or so. > > thanks, > > greg k-h >
We have been building and boot testing the mainline 4.9 tree for quite some time. This issue appears to be exposed by the rootfs that Linaro is using for testing; ours is incredibly simple (prints the version string then shuts down, there is no systemd or complex init). Some initial notes, I am not sure how much time I will have to look at this in the near future: 1. This does not happen with the same configuration file on linux-4.14.y. 2. This happens with the latest version of clang on linux-4.9.y. 3. Bisecting v4.9 to v4.14 will be rather difficult because clang support was backported to 4.9 somewhere in the 130s. There could be a clang backport missing or a bug was unintentionally fixed somewhere else. Cheers, Nathan
